Enclosed find a report and diagnosis for each female rat in the Dow Study 'Acrylonitrile in drinking water'. A two year drinking water chronic toxicologic oncogenicity study. There were multiple brain sections from forty-five rats. There were twelve animals without brain tumors. There were thirty-three animals with primary brain tumors. Some of the animals evidenced two tumors. There was one animal with an undifferentiated malignant meningeal tumor. This may have been a malignant pinealoma, although special stains would be needed to verify this diagnosis. There were four animals with pinealomas; two of these animals also had astrocytomas. There were three animals with mixed gliomas containing both astrocytic and oligodendroglial neoplastic cells. There were twenty-seven animals with astrocytomas. While I believe the incidence of primary brain tumors in rats is higher than most laboratories seem to report, I can only conclude an oncogenic effect especially in regard to astrocytomas and pinealomas in this experimental series of rats. This pinealoma, in my opinion, is an exceedingly rare tumor in the rat.